Basal cell adenoma of the parotid gland

Canalicular adenoma: palatal presentation of an uncommon lesion

Canalicular adenoma is a unique, rare, benign salivary gland neoplasm whose reported prevalence varies in different studies. According to literature, this neoplasm has a marked predilection to occur in the upper lip of elderly women. Histological features are usually distinctive and diagnostic. This neoplasm has good prognosis after conservative surgical management but the propensity of multifocal nature and recurrence of this lesion mandates regular follow-up. This case report illustrates the case of a canalicular adenoma in the palate in a 71-year-old male patient. Here, we discuss the differential diagnosis with a brief review of literature.

Basal cell adenoma-an unusual presentation

Basal cell adenoma is an uncommon epithelial neoplasm of the salivary gland most commonly arising in the parotid glands. We report a case of basal cell adenoma of the minor salivary gland presenting as a slowly progressing, large parapharyngeal mass. Histopathology revealed a well-encapsulated mass with characteristic histomorphology. Immunohistochemistry showed selective positivity for pancytokeratin, S-100, and smooth muscle actin in the tumor which highlighted the participation of myoepithelial cells in histogenesis. In addition, positivity was noted for carcinoembryonic antigen and vimentin. Ultrastructural analysis showed characteristic features including reduplicated basal laminae around the tumor cells, presence of intermediary filaments, and rough endoplasmic reticulum in the cytoplasm. There are no reports of basal cell adenoma presenting as a parapharyngeal mass lesion in the available English literature. This case highlights the rarity of this tumor with regard to its site of origin, possibly from a minor salivary gland.

Salivary gland basal cell and canalicular adenomas: immunohistochemical demonstration of myoepithelial cell participation and morphogenetic considerations

OBJECTIVE

To evaluate cellular composition of salivary gland adenomas using 3 monoclonal antibodies that recognize a smooth muscle phenotype confirmed to be sensitive for myoepithelial differentiation.

DESIGN

Immunohistochemical evaluation of 25 salivary gland basal cell and canalicular adenomas.

SETTING

Archival pathology material from the files of Henry Ford Hospital, Detroit, Mich, and the University of California at San Francisco.

RESULTS

All basal cell adenoma variants exhibit some degree of myoepithelial cell participation with periductal, epithelioid, and spindled (stromal-like) morphologic structures. Only the canalicular adenomas, even if mixed with trabecular and solid patterns, are devoid of staining with these 3 antibodies, suggesting an adenoma composed exclusively of ductal luminal cells.

CONCLUSIONS

There is an overlapping histomorphologic and common cellular composition of the basal cell adenoma variants with other recognized adenomas, such as pleomorphic adenoma and myoepithelioma. Relative differentiation toward 3 cell phenotypes (ductal luminal, basal, and myoepithelial) and the character of extracellular matrix production in varying proportions by the neoplastic myoepithelial cells distinguishes the spectrum of salivary gland adenomas identified in current classification schemes.

The cellular composition of basal cell adenoma of the parotid gland: an immunohistochemical analysis

Four cases of basal cell adenoma of the parotid gland were examined immunohistochemically to characterize their cellular composition. In all cases epithelial membrane antigen and keratin were detected in the inner luminal cells; some cells also showed positive staining for secretory functional markers, indicating their differentiation toward secretory epithelium. In tubular and trabecular types the outer cells consistently displayed an intense staining for vimentin and some were also positive for actin, indicating their myoepithelial nature. In the solid type, most tumor cells resembled the ductal cells or basal cells of larger ducts in normal gland with regard to their immunoreactivity. Our results may suggest that the proportion and arrangement of heterogeneous tumor cells are responsible for different histologic patterns of the salivary basal cell adenoma.

Basal cell adenocarcinomas of the major salivary glands

Basal cell adenoma of salivary gland has become an established variant of monomorphic adenoma since its segregation from pleomorphic adenoma in 1967. Although there have been many comprehensive reports about benign basal cell adenomas, only rare case reports of malignant basal cell type neoplasms have appeared in the literature. Described in this report are the clinicopathologic features of 29 cases labeled basal cell adenocarcinomas that had morphologic characteristics of basal cell adenomas but infiltrative, perineural, and intravascular growth features that indicated a malignant potential. With limited follow-up, seven tumors are known to have recurred, and three of these metastasized to lymph nodes and lung. One patient died with extensive local spread of the tumor. All patients were adults. The peak incidence was in the sixth decade of life, and there was no gender predilection. The parotid gland was the predominant site. A solid type growth configuration was most frequent; membranous, trabecular, and tubular types were less frequent, in that order. Three patients also had dermal cylindromas, perhaps indicative of a salivary gland-skin adnexal diathesis that has been previously reported.

Basal cell adenomatosis of minor salivary glands of the upper lip

The basal cell adenoma is one of the more commonly occurring types of salivary tumors in the upper lip. A case with multiple (five) tumors is presented and the literature reviewed. This lesion would be more correctly designated as an adenomatosis. In spite of its frequent multicentricity, recurrence is unusual following surgical removal.

Normal and neoplastic myoepithelial cells in salivary glands: an immunohistochemical study

To determine the difference between normal and neoplastic myoepithelial cells, we performed immunoperoxidase staining for contractile proteins (actin and myosin) and intermediate filament proteins (vimentin and 55- to 57-kilodalton keratin) on paraffin sections from salivary gland tumors. Normal myoepithelial cells were positive for actin and myosin but negative for vimentin and keratin. Outer tubular cells of organoid double-layered tubular structures seen in pleomorphic and monomorphic adenoma and adenoid cystic carcinoma, and "cyst"-lining cells and outermost cells of adenoid cystic carcinoma were occasionally positive for actin and myosin. These outer tubular cells, "cyst"-lining cells, and outermost cells were considered to be neoplastic myoepithelial cells. However, their stainability was much lower than that of normal myoepithelial cells. On the other hand, these neoplastic myoepithelial cell were always positive for vimentin. "Mesenchymal" cells and hyaline cells of pleomorphic adenoma and indifferent cells of adenoid cystic carcinoma were negative for both actin and myosin but positive for vimentin and occasionally also positive for keratin. The significance of vimentin staining in neoplastic myoepithelial cells and the coexpression of vimentin and keratin in some tumor cells is discussed.

Myoepithelial cells in salivary gland tumors--revisited

It is an interesting parallel that the myoepithelial cell with its hybrid epithelial and mesenchymal structural and functional phenotype has a dual role in such salivary gland tumors as pleomorphic adenoma. This cell is responsible for considerable proportions of the epithelial component of this tumor, including squamous metaplasia, and is also the agent principally involved in the synthesis, organization, and cytologic modifications of the chondromyxoid regions. Neoplastically modified myoepithelial cells are also generally accepted to be a significant component of salivary gland tumors such as epithelial-myoepithelial carcinoma, certain adenocarcinomas, and, of course, myoepitheliomas. The range of myoepithelial cell alterations can be appreciated via ultrastructural assessment of the above four classes of salivary gland tumors. An electron microscopic survey of monomorphic adenomas, adenoid cystic carcinomas, and mucoepidermoid carcinomas reveals some having a tumor cell component with structural modifications and localization similar to the modified myoepithelial cells in pleomorphic adenomas and the adenocarcinomas noted above. Such ultrastructural findings have important implications for clarifying diagnostic problems, for understanding histogenetic relationships, and for improving the classification of salivary gland tumors.

Canalicular adenoma: not a basal cell adenoma

The evidence that canalicular adenomas and basal cell adenomas are separate entities is presented in this article. The clinical features were studied in a series of 13 previously unreported salivary gland tumors (5 canalicular adenomas and 8 basal cell adenomas) and 99 examples derived from the literature (68 canalicular adenomas and 31 basal cell adenomas). Representative tumors from the new cases and from 66 referred cases were studied by histologic, histochemical, and electron microscopic techniques. The two tumors differ significantly with respect to the age range of affected patients, site of predilection, and morphologic and histochemical features.

Monomorphic adenomas of the parotid glands. Their ultrastructure and histogenesis

Three cases of monomorphic basal cell adenoma of the parotid glands were studied with light microscopy. In one patient, fresh tissue was available for electron microscopic observations. On the basis of ultrastructural findings it was concluded that myoepithelial cells play little, if any, role in the histogenesis of this lesion. The tumor originates from the undifferentiated stem cells analogous to the cells seen at the "end bud" stage of salivary gland morphogenesis prior to their further cytodifferentiation and functional maturation into secretory and myoepithelial cells. In fully developed salivary glands such undifferentiated stem cells reside as "reserve" cells in the intercalated ductal system.

Basal cell adenoma with acinic differentiation

A case of basal cell adenoma in the left parotid region of a 45 years old male was reported. The tumor measured 1.1 cm X 0.9 cm, was spherical and covered with a fibrous capsule. Histologically, it was a monomorphic adenoma, forming solid, trabecular, tubular and acinic structure. The tumor cells secreted PAS-positive substance. Electron microscopically, the tumor consisted of three kinds of cells - secretory cells containing electron-dense secretory granules, non-secretory cells, and myoepithelial cells. The acinus was formed of single-layered secretory cells, in the base of which myoepithelial cells were observed. The tubulus was formed of both secretory and non-secretory cells, and myoepithelial cells were found in the base of the tubules. The interstitium was narrow, and was composed of a small amount of collagen fibers, myoepithelial cells, and basement membrane-like substance.

Monomorphic adenomas of the major and minor salivary glands. Report of twenty-one cases and review of the literature

Monomorphic adenomas are benign salivary gland tumors that have a predilection for development in the upper lip and parotid gland. Typically, patients are older persons (mean age, 61 years), but a broad age range (32 to 87 years) has been reported in the literature. Adequate treatment consists of superficial or total parotidectomy (depending on extent and location of the tumor) for parotid lesions and excision with a limited border of normal tissue for minor gland tumors. Uniform cellularity, lack of myxoid or chondroid features, and a tendency for multicentric origin are features which separate these tumors from pleomorphic adenomas. Monomorphic adenomas have been mistakenly diagnosed and treated as adenoid cystic carcinomas. Close attention to cytologic detail, histomorphology, and growth pattern at the periphery are important in separating these tumors.

Morphologic changes in rat parotid following isoproterenol administration and fractionated x-irradiation

The effects of fractionated X-irradiation following isoproterenol (IPN) administration on rat parotid gland were studied 4, 8, and 12 weeks post-irradiation. Degenerative and necrotic changes of the acinar cells were observed at all three time intervals as a result of the radiation. These changes were more obvious 4 and 8 weeks post-irradiation and isoproterenol administration. The necrotic acinar cells were replaced by fibrous connective tissue, especially conspicuous at 12 weeks. Reparative changes were observed along with the degenerative and regressive phenomena of the gland. Enlarged acinar cells and nuclei were observed as early as 4 weeks post-irradiation. This change was focally distributed at the 4-week interval but more widespread 8 and 12 weeks post-irradiation. Mitochondrial hyperplasia with alteration of mitochondrial cristae was observed 12 weeks post-irradiation. Proliferation of cells of ductal origin and nodular proliferation of ducts were observed 12 weeks after isoproterenol administration plus X-irradiation. These proliferative phenomena may represent an early stage of tumor formation resulting from the combined effect of isoproterenol and X-irradiation on rat parotid gland.

Dermal analogue tumours of major salivary glands

Monomorphic adenomas of the major salivary glands manifest a histologic spectrum whose diversity rivals that of pleomorphic adenomas. In nearly all forms of monomorphic adenomas there are histologic features which recall stages in the embryonic development of salivary glands and/or adenexae of skin. A close histogenetic relationship between certain monomorphic adenomas and certain adenexal tumours of skin is suggested by the findings of this report. Within the diversity of expression found in monomorphic adenomas are subsets of tumours which are analogous and nearly homologous with dermal appendage tumours, especially the dermal eccrine cylindroma. The analogous relationship is carried further by a proposed diathesis in which patients exhibit histologically similar tumours in their salivary glands and skin.

Basal cell adenomas of the minor salivary glands. A clinicopathologic study of seventeen new cases and a review of the literature

The basal cell adenoma (BCA) is a benign monomorphic salivary gland tumor. Those of minor gland origin tend to occur within or adjacent to the upper lip (80 percent). The BCA is an encapsulated, slow-growing lesion which most commonly affects older persons. Several different histologic patterns can be noted, and often a combination of these variations is present within the same tumor. Simple surgical excision appears to be adequate treatment.

Canalicular adenoma of the upper lip: an electron microscopic study

Canalicular adenoma is composed of a row of tall columnar cells adjacent to canalicular lumina and a row of conical cells adjacent to connective tissue stroma. It differs from basal cell adenoma, of the parotid by the lack of well developed desmosomes associated with bundles of tonofilaments; by the presence of moderate numbers of cellorganelles; by a single, inconspicuous basal lamina instead of multi-layering; and by the presence of mucoid material in the stroma. Results suggest that this type of tumor should be considered a specific benign entity of the salivary glands. Cytologic features also suggest that it originates in excretory duct cells of minor salivary glands.

A case report of basal cell adenoma showing elastic fiber (elastin-basement membrane complex) formation of the submandibular gland

A biopsy case of basal cell adenoma of the submandibular gland was reported in a 15-year-old boy. The tumor was pigeon's egg-sized, spherical in shape and encapsulated by fibrous tissue, and its cut-surface was grayish white. Histologic feature of this neoplasm was a trabecular or tubular monomorphic adenoma with well-developed elastic fibers (elastin-basement membrane complex) in the interstitial tissue. Electron microscopy disclosed 4 kinds of tumor cells, that is, secreting cells, squamous cell-like cells with tonofibrils and tonofilaments, clear cells with a few filaments, and myoepithelial cells. The interstitium contained elastin, collagen fibrils and basement membrane-like substance. Possible production of elastic fibers by the myoepithelial cells of this adenoma was discussed.

Ultrastructural features of monomorphic adenoma of the parotid gland

A monomorphic adenoma of the parotid gland (basaloid type) was studied with the electron microscope. In general, the tumor consisted of a single cell type, except in areas of squamous metaplasia. The cells were polygonal with prominent nuclei and scant cytoplasmic organelles. Intercellular junctions and plasmalemmal projections (filopodia) were conspicuous. Myoepithelial cells and secretory granules were absent. On the basis of these ultrastructural features, it is proposed that the interlobular duct, rather than the intercalated duct, is the probable site of origin of this tumor.

Oral granular-cell tumors. Report of twenty-five cases with electron microscopy

Twenty-five cases of granular-cell tumor of the oral cavity are reported. The clinical findings are similar to previously published data. Of five cases studied by electron microscopy, three were processed directly from fresh surgical specimens and two cases were processed following initial formalin fixation. The granules for the most part are morphologically compatible with lysosomes except for a single variety containing viruslike particles. There is increasing evidence in support of a neural origin, but the indications are that more than one cell type may be the progenitor of granular cells of the granular cell tumor.

Membranous basal cell adenoma of parotid gland, dermal cylindromas, and trichoepitheliomas. Comparative histochemistry and ultrastructure

A basal cell adenoma of parotid, eccrine dermal cylindromas and trichoepitheliomas occurring in the same patient were examined by light and electron microscopy and histochemistry. The eccrine and parotid adenomas were similar both structurally and histochemically except for the presence of Langerhans cells in the cutaneous adenoma and well differentiated mucinous cells in the parotid tumor. The three different hamartomas found in this individual may represent the effect of a single pleiotropic gene acting on ontogenetically related stem cells.

Monomorphic adenomas of salivary glands. Trabecular-tubular, canalicular, and basaloid variants

Eleven cases of monomorphic adenoma of the salivary glands are interpreted as variants of pleomorphic adenomas (mixed tumors) that lack chondroid or myxomatous components. Nine of these tumors were in the parotid gland and two were on the hard palate. Monomorphic adenomas are usually encapsulated and frequently are partially cystic. Their histologic pattern may be confused with that of adenoid cystic carcinoma, but they grow in an expansile fashion and usually are monolobular. Histologically, they may be divided into trabecular-tubular, canalicular, and basaloid variants. Morphologically, they bear a resemblance to basaloid sweat-gland tumors (eccrine spiradenoma and cylindroma).

Basal cell adenoma of the parotid gland. Case report with ultrastructural observations

A case of basal cell adenoma of the parotid gland is reported. The tumor was studied by electron microscopy, and fine structural features included numerous desmosomes, large secretory granules, and replication of the basal lamina. Myoepithelial cells were not observed. The observations support the view that the tumor is monomorphic and that it arises from serous cells of the acini or intercalated ducts. The tumor may be the benign homolog of the adenoid cystic carcinoma.

[Morphology of salivary gland diseases]

The human salivary glands represent a functional system with manifold responsibilities and interactions to the organism. The major and minor salivary glands show a common construction schedule consisting of an acinar functional system for the production of an enzyme- and mucin-containing primary saliva and a ductal functional system with manifold secretory, resorptive and regulatory responsibilities for the transport and the definitive composition of the saliva. The cyclic AMP and calcium iones localized in the glandular acini have an exceptional importance for the course of the secretory process. The neurohormonal control of the salivary secretion results by adrenergic and cholinergic transmitter substances. Moreover the secretory process shows a daily cycle combined with morphological alterations of the glandular cells (so called circadian structures). The fluid secretion of the salivary duct system (the output of sodium-, potassium- and chlorine-iones) represents an active energy-consumed transport process which will be regulated by several factors (autonomic nervous system, quantity of perfusion, hydrostatic pressure in the blood capillaries, transepithelial active transport by ATP-consumed pump systems). The striated ducts are the functional most important sector of the duct system for a rapid fluid- and electrolyte excretion. The terminal axons of the postganglionic sympathic and parasympathic neurits are characterized by spindle-shaped enlargements (varicosities) which contain neurosecretory granules. In the region of the acinar and intercalated duct cells a direct synaptic contact exists for the stimulation transmission, in the course of which the terminal axon contacts immediately with the effector cell by penetration of the basement membrane. The salivary glands form a part of the stabil tissues with reversible postmitotic cells in regard of the tissue regeneration. Under pathological conditions (inflammations, impediment of secretion fluid, radiation effects etc.) metaplasias and proliferations of the duct system arise with development of indifferent duct formations analogous to the type of an embryonal salivary gland. The terminal zone between intercalated and striated ducts represents an indifferent zone with large regeneratory potency. A special behaviour shows the myoepithelial cells which are developed as well to the outside of primitive embryonic duct buds as differentiated intercalated and striated ducts. Morphologically three types of diseases can be classified in the salivary glands: sialadenosis, sialadenitis and tumours.(ABSTRACT TRUNCATED AT 400 WORDS)